"On three separate occasions, a research team spotted young male seals sexually coercing what appeared to be healthy penguins of unknown gender.All four known sexual incidents followed a common pattern. Each time a seal chased, captured and mounted the penguin. The seal then attempted copulation several times, lasting about five minutes each, with periods of rest in between.Male and female penguins mate via an opening called a cloaca, and the seals are thought to have actually penetrated the penguins in some of the acts, which were caught on film.In three of the four recorded incidents the seal let the penguin go. But on one of the more recent occasions, the seal killed and ate the penguin after trying to mate with it.The incidents are the only time pinnipeds, the group that includes seals, fur seals and sea-lions, have been known to have sex with an animal from a different biological class, in this case a mammal trying to have sex with a bird.The scientists can only speculate about why the seals are behaving this way."